This invention relates in general to new and useful improvements in boat engine mountings, and more specifically to the mounting of an inboard engine or a so-called inboard-outboard engine on stringers of a boat hull.
In the conventional manufacture of boats to be powered by one or more inboard engines or so-called inboard-outboard engines, the engine or engines are mounted on and supported by stringers, the name commonly applied to the elongate inboard frame members which extend in fore-and-aft directions along the very bottom of the hull. The stringers are often formed of a laminated wood core encased in a heavy fiberglass-reinforced coating, the laminae or plies of the core extending longitudinally in substantially vertical planes. However, the stringers may be formed of any suitable material such as rigid foamed plastics, solid hardwood, and aluminum or other metals, and though in modern boat construction the stringer material is usually covered by a fiberglass-reinforced coating, this is not always the case. In any event, it will be apparent from the following specification that the present invention is not limited to any particular stringer construction.
However, the features, objects and advantages of the invention may be suitably explained and understood with reference, by way of example, to stringers having laminated wooden cores encased in fiberglass, as first mentioned hereinabove. In the case of such a stringer, if the engine mounts were to be secured by threaded fasteners such as conventional lag bolts, driven vertically into an unmodified stringer from its upper surface, the fasteners would not hold for long in its laminated structure.
As is shown in the accompanying drawings and explained with greater particularity hereinbelow, one expedient presently employed to deal with this problem is to form a notch or recess at the upper part of the stringer, and before the fiberglass coating is applied, to fit a complementary insert of solid hardwood into the notch. The fiberglass coating covers the insert as well as the remainder of the stringer, and the engine mount may readily be secured by a lag bolt or lag bolts driven through the fiberglass and into the solid insert.
Also shown in the accompanying drawings and explained with greater particularity hereinbelow is another expedient commonly employed in which a notch is cut in the upper profile of the stringer. In this instance, however, the fiberglass coating is applied to the stringer so notched, and a custom-made cap is then received over the stringer to extend across the notch, the cap being secured to the stringer by transverse bolts. The boat engine mount is then directly bolted to the cap and secured by a fastening nut or nuts accommodated in the space below the cap provided by the notch.
Both of these prior constructions are subject to significant disadvantages which are set forth hereinbelow.